Knives and other blades traditionally have been sharpened by hand using a sharpening stone. The stone is held in one hand while the knife is held in the other and rubbed against the stone. However, this method of sharpening knives can be dangerous since the blade can slip from the stone and cut the hand holding the stone. Further, the knife must be turned to sharpen both sides of the knife blade, which is tedious and time-consuming and which requires some practice to achieve good sharpening.
Although various knife sharpeners have been available heretofore having pairs of sharpening elements between which the knife blade is drawn, the sharpeners of the prior art have not been altogether satisfactory. In particular, the prior knife sharpeners have not been adapted to provide continuous adjustment of the angle between the sharpening elements and continuous adjustment of the surface portions of the sharpening elements across which the knife blades are drawn, in order to obtain precise sharpening. For example, U.S. Pat. No. 4,259,815 to Kuban shows a device wherein the sharpening members pivot from secured positions in a handle to upwardly inclined extended positions defined by stops which do not provide for either angular or rotational adjustment. U.S. Pat. Nos. 3,894,362 to Graves and 1,429,984 to Vollmer show devices wherein the sharpening members are secured in fixed angular relationship but can be rotationally adjusted to present fresh surfaces to the bladed edges. U.S. Pat. No. 4,231,194 to Glesser shows a device wherein the sharpening members can be located in different discrete orientations on a base, but cannot be continuously adjusted in either manner.
It will be appreciated that achieving and maintaining precise knife sharpening is important to butchers and meat cutters, who must periodically stop their work to resharpen their knives. Dull knife blades contribute toward fatigue and reduced productivity. Heretofore, however, there has not been available a knife sharpener which provides for continuous adjustment of the angle between the sharpening elements and their work surfaces in a safe and convenient manner so as to facilitate precise knife sharpening. There is thus a need for such an improved sharpener.